UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Amateur and Military Radio

Notices

Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

Reply
 
Thread Tools
Old 13th Dec 2019, 5:34 pm   #1
ORAWA01
Hexode
 
Join Date: Apr 2011
Location: Stirlingshire, UK.
Posts: 290
Default NCX-5 powered by NCX-A keeps blowing fuse

Hi All

I powered on the NCX-5 hf rig connected to the NCX-A psu, and it keeps blowing the fuse. It has a glass fuse at the back rated at 4A.

I replaced the fuse to a fresh new one, and connect the NCX-A into the mains which is a 110V step down transformer. The fuse is not blowing in the NCX-A at this moment.

It is when the NCX-5 is powered on, at that moment, the fuse blows. The blown fuse shows a burn all around its glass.

What could the cause for this? I was thinking that the NCX-A psu is OK (it has been fully recapped recently with high quality parts), but the rig itself NCX-5 has problem. But what do you think? Any ideas?

Thanks

Last edited by ORAWA01; 13th Dec 2019 at 5:43 pm.
ORAWA01 is offline   Reply With Quote
Old 13th Dec 2019, 6:23 pm   #2
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,645
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Whereabouts in the circuit is the fuse located? In the mains supply to the PSU, in the output from the PSU, or in the HF rig?
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 13th Dec 2019, 6:52 pm   #3
ORAWA01
Hexode
 
Join Date: Apr 2011
Location: Stirlingshire, UK.
Posts: 290
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Quote:
Originally Posted by Station X View Post
Whereabouts in the circuit is the fuse located? In the mains supply to the PSU, in the output from the PSU, or in the HF rig?
It is in the mains supply to the PSU.
ORAWA01 is offline   Reply With Quote
Old 13th Dec 2019, 7:39 pm   #4
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,189
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Possibly a short rectifier diode, if it has them. Worst possible mains transformer. I am assuming that powering on the rig switches the mains to the power supply.

Should not be difficult to trace.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 13th Dec 2019, 10:09 pm   #5
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,645
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Circuit courtesy of BAMA.

Full manual available here:-

http://bama.edebris.com/manuals/national/ncx3/

Switching on the transceiver shorts pins 1 and 2. I'd try disconnecting the PSU from the rig and shorting pins 1 and 2 to see if the fuse blows. Be very careful though. You don't want a 700 VDC shock!
Attached Thumbnails
Click image for larger version

Name:	NCX-A.jpg
Views:	120
Size:	47.9 KB
ID:	195311  
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 13th Dec 2019, 11:39 pm   #6
ORAWA01
Hexode
 
Join Date: Apr 2011
Location: Stirlingshire, UK.
Posts: 290
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Thank you for your info & advice on this problem.

All the fuses in my tool tray has run out this afternoon, as the NCXes kept blowing them off when powered on, and I kept on trying with different settings on the rig. I placed an order for 10 more fuses this evening. When they arrive, I will have a go again.
ORAWA01 is offline   Reply With Quote
Old 14th Dec 2019, 9:55 am   #7
dodgy-dxer
Hexode
 
dodgy-dxer's Avatar
 
Join Date: Mar 2008
Location: Newmarket, Suffolk, UK.
Posts: 316
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Has the PSU ever worked since it was recapped?

Fred
dodgy-dxer is offline   Reply With Quote
Old 14th Dec 2019, 10:54 am   #8
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,189
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Diodes worth a check first, then make sure that cap is correct way around at bottom of circuit.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 14th Dec 2019, 12:20 pm   #9
robinshack
Octode
 
robinshack's Avatar
 
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 1,094
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

When you get new fuses, may be worth a try with a lamp limiter if dc resistance checks are inconclusive.
Rob
__________________
I am also interested in and collect 00 model railway.
robinshack is offline   Reply With Quote
Old 14th Dec 2019, 12:23 pm   #10
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,645
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

I think we've been there:-

https://www.vintage-radio.net/forum/...d.php?t=161363

Good idea nevertheless.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 14th Dec 2019, 2:15 pm   #11
robinshack
Octode
 
robinshack's Avatar
 
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 1,094
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Ok Graham, my memory is not as good as yours!
Rob
__________________
I am also interested in and collect 00 model railway.
robinshack is offline   Reply With Quote
Old 14th Dec 2019, 2:20 pm   #12
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,645
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Don't you believe it. I have "Bottom of the stairs" moments as well as "Top of the stairs" ones!
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 14th Dec 2019, 7:20 pm   #13
ORAWA01
Hexode
 
Join Date: Apr 2011
Location: Stirlingshire, UK.
Posts: 290
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Quote:
Originally Posted by dodgy-dxer View Post
Has the PSU ever worked since it was recapped?

Fred

I am not sure. It had been recapped by the previous owner.
I am trying to power it on for the 1st time since I got them long time ago.

Last edited by ORAWA01; 14th Dec 2019 at 7:27 pm.
ORAWA01 is offline   Reply With Quote
Old 14th Dec 2019, 7:22 pm   #14
ORAWA01
Hexode
 
Join Date: Apr 2011
Location: Stirlingshire, UK.
Posts: 290
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

When the PSU arrived to me, the fuse was already burnt.
The PSU is marked as 110V. Is there any possibility that someone might have had plugged it into 230V accidentally, and burnt the fuse?
ORAWA01 is offline   Reply With Quote
Old 14th Dec 2019, 7:25 pm   #15
ORAWA01
Hexode
 
Join Date: Apr 2011
Location: Stirlingshire, UK.
Posts: 290
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Quote:
Originally Posted by Station X View Post
I think we've been there:-

https://www.vintage-radio.net/forum/...d.php?t=161363

Good idea nevertheless.
Still didn't manage to get / make lamp current limiter. But would circuit breaker and fuses do the same job? = if over voltage or over current flows, then they will trip, or burn / blow?
ORAWA01 is offline   Reply With Quote
Old 14th Dec 2019, 7:26 pm   #16
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 15,645
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Quote:
Originally Posted by ORAWA01 View Post
Is there any possibility that someone might have had plugged it into 230V accidentally, and burnt the fuse?
100 percent chance I'd say, but the fuse probably saved it.
__________________
Graham. Forum Moderator

Keep the soldering iron hot.
Station X is online now   Reply With Quote
Old 14th Dec 2019, 8:56 pm   #17
robinshack
Octode
 
robinshack's Avatar
 
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 1,094
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

"Still didn't manage to get / make lamp current limiter. But would circuit breaker and fuses do the same job? = if over voltage or over current flows, then they will trip, or burn / blow?"

Without technical info to back this up, if it were me I would expect the fuse to blow and the trip maybe trip as well? If I had a limited number of fuses, then I would use the lamp limiter for certain.
All depends on just how many fuses you wish to sacrifice!
Rob
__________________
I am also interested in and collect 00 model railway.
robinshack is offline   Reply With Quote
Old 14th Dec 2019, 9:03 pm   #18
Cobaltblue
Dekatron
 
Cobaltblue's Avatar
 
Join Date: Dec 2010
Location: Exeter and Poole, UK.
Posts: 3,457
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Letting the equipment just blow fuses is harsh.


The current required to blow a fuse as you have described runs the risk of damaging something else.


A lamp limiter allows you to see faulty behaviour without risking hard to replace parts.


Whilst trying to find the cause of the fuse blowing you need to reduce the available current to more manageable levels.


Time to get your limiter built and your meter out.


Cheers


Mike T
__________________
Don't care if it was a bargain why's it in my kitchen
Mike T BVWS member.
www.cossor.co.uk
Cobaltblue is offline   Reply With Quote
Old 14th Dec 2019, 9:07 pm   #19
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,189
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

Have the bridge rectifier diodes been checked ok yet?
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is offline   Reply With Quote
Old 14th Dec 2019, 10:19 pm   #20
ORAWA01
Hexode
 
Join Date: Apr 2011
Location: Stirlingshire, UK.
Posts: 290
Default Re: NCX-5 powered by NCX-A keeps blowing fuse

I had 2x fuses, which both blown. I put another one in, but it is underrated one at 0.5A.

The books says, it takes 3.7A for transmit, and 1.5A to receive. So when the rig is being powered on, it will draw at least 1.5A.

So, I am not powering it on now, but when the PSU is plugged into the mains, it is live, when checked with NCV DMM. So, the PSU itself is not blowing the fuse, when live. It is only when the rig gets switched on, it blows the fuse.

Now and for a few days, I have other things to clear, and organise, so they are put away for now. But will get them out and have a look again. If I could get more ideas where to look and check, that would be great. Thanks.
ORAWA01 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 7:43 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.